I second the vote for Bill Bryson - his books and his narration are very enjoyable.

Freakonomics by Steven Levitt and Stephen Dubner is also great - like the Bill Bryson books, it's perfect for listening to over long periods of time with frequent interruptions and traffic distractions.

I also highly recommend CS Forester's Horatio Hornblower novels, narrated by Geoffrey Howard (stay away from the versions narrated by Christian Rodska: he has one of the world's most irritating voices). These books might not be as well known on your side of the pond, so here is a link for more info: Hornblower. These are my all time favourite audiobooks.